A recent pubication on QUASAR (NIDA Research Monograph No. 22; DHEW No. ADM 78-729, (1978)) has emphasized the importance of structure-activity relationships in the design of drugs and in understanding their mode of action. The report made it clear that a comprehensive study of structure-reactivity relationships for a large variety of chemical reactions was a necessary component in the overall endeavor. Its the purpose of the research described in this proposal to test a new and wide-ranging theory of structure-reactivity relationships for unimolecular reactions of organic molecules. If the reliability of this theory can be firmly established by experimental test, it may well have direct applicability to projects like QUASAR and to the rational development of strategies for the synthesis of new drugs.